The talk I'll be giving will be:
Reactive streams - Play's Iteratee API
If people want, I can prepare presentations on the other ones another time.
As for the presentation on Iteratees, I'm interested in knowing if anyone has ever used them, whether in Play, Haskell, Scalaz or something else? I'm going to aim my presentation fairly low, starting with what it means to handle streams reactively, through to what the requirements of our interfaces should be to do so, and then from there introduce Iteratees.